eu.fbk.knowledgestore.triplestore

Class RewritingTripleStore

java.lang.Object

com.google.common.collect.ForwardingObject

eu.fbk.knowledgestore.triplestore.ForwardingTripleStore

eu.fbk.knowledgestore.triplestore.RewritingTripleStore

All Implemented Interfaces:

Component, TripleStore, Closeable, AutoCloseable

public final class RewritingTripleStore
extends ForwardingTripleStore

A TripleStore wrapper that rewrites URIs, adapting a prefix used externally in the KS to a prefix used internally to the wrapped triple.

The wrapper intercepts calls to an underlying TripleStore and to the TripleTransactions it creates. It rewrites any incoming URI starting with a configured external prefix, replacing that prefix with an internal replacement. At the same time, the wrapper rewrites every outgoing URI starting with the internal prefix, replacing that prefix with the external one. Rewrite occurs on every input / output data item exchanged at the level of the TripleStore API, including RDF values, statements, binding sets and SPARQL queries (query rewriting is done by manipulating their algebraic form).

Constructor Summary

Constructors

Constructor and Description
RewritingTripleStore(TripleStore delegate, String internalPrefix, String externalPrefix) Creates a new instance for the wrapped TripleStore specified.

Method Summary

Modifier and Type	Method and Description
TripleTransaction	begin(boolean readOnly) Begins a new read-only / read-write triple store transaction.
protected TripleStore	delegate()

Methods inherited from class eu.fbk.knowledgestore.triplestore.ForwardingTripleStore

close, init, reset

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RewritingTripleStore

public RewritingTripleStore(TripleStore delegate,
                            String internalPrefix,
                            String externalPrefix)

Creates a new instance for the wrapped TripleStore specified.

Parameters:

delegate - the wrapped TripleStore

internalPrefix - the internal (i.e., in the TripleStore) prefix of the URIs to rewrite

externalPrefix - the external (i.e., in the KS API) prefix of the URIs to rewrite

Method Detail

begin

public TripleTransaction begin(boolean readOnly)
                        throws IOException

Description copied from interface: TripleStore

Begins a new read-only / read-write triple store transaction. All the accesses to a triple store must occur in the scope of a transaction, that must be ended (possibly committing the modifications done) as soon as possible to allow improving throughput.

Specified by:

begin in interface TripleStore

Overrides:

begin in class ForwardingTripleStore

Parameters:

readOnly - true if the transaction is not allowed to modify the contents of the triple store (this allows for optimizing the access to the triple store).

Returns:

the created transaction

Throws:

DataCorruptedException - in case a transaction cannot be started due to triple store files being damaged or non-existing; a TripleStore.reset() call followed by a full triple store re-population should be attempted to recover this situation

IOException - if another IO error occurs while starting the transaction, not implying a data corruption situation

delegate

protected TripleStore delegate()

Specified by:

delegate in class ForwardingTripleStore